1. Field of the Invention
This invention relates to an engine of a remote control model, particularly to an improvement of its carburetor.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, a conventional carburetor body 10 is provided with an axial hole 11 bored axially, a throttle 12 installed movably in one side of the axial hole 11, and a guiding sleeve 14 installed in the other side of the axial hole 11. The throttle 12 is provided with a throttle hole 121 that is screwed with a second needle 13. The guiding sleeve 14 is screwed with a third needle 15 provided with an injection nozzle 151 corresponding to a needle valve 131 provided in the second needle 13. There is a threaded hole 141 bored vertically throughout the guiding sleeve 14 and the carburetor 10 for being fixedly engaged with a main needle 16, which is provided with a fuel inlet nozzle 161 located aside to let fuel pass through to be jetted out from the injection nozzle 151.
However, with the throttle 12 and the second needle 13 installed in one side of the axial hole 11, and the guiding sleeve 14 and the third needle 15 installed in the other side, there are three sets of progressive tolerance possibly happening at two sides of the axial hole 11 respectively while assembling owing to too many components closely assembled together, apt to downgrade precision. As shown in FIG. 3, during the assembly of the components mentioned above, there are relatively at least six sets of progressive tolerance created to keep center lines L and L1 that should be aligned between the needle valve 131 and the injection nozzle 151 deviated. Thus, the gap between the needle valve 131 and the injection nozzle 151 may become unsmooth to cause an uneven fuel injection, affecting fuel control. In addition, an end 152 of the third needle 15 is extended into a mixing chamber 17, which is formed between the throttle 12 and the guiding sleeve 14 to let fuel and air to mix up, to reduce the space of the mixing chamber 17.